Introdução. O efeito da dieta e da dieta associada ao treinamento físico na resposta vasodilatadora e no controle autonômico cardíaco durante manobras fisiológicas ainda não foram estudados em crianças obesas. Portanto, o objetivo deste estudo foi demonstrar que: 1) o controle autonômico cardíaco pode estar alterado na criança obesa; 2) a resposta de pressão arterial e a resposta vasodilatadora podem estar alteradas na criança obesa durante o exercício isométrico e o estresse mental; 3) dieta e treinamento físico podem melhorar o controle autonômico cardíaco; e 4) dieta associada ao treinamento físico restaura a resposta de pressão arterial e a resposta vasodilatadora durante manobras fisiológicas em crianças obesas. Métodos e Resultados. Trinta e nove crianças obesas (10±0,2 anos) foram randomizadas e divididas em dois grupos: Dieta associada ao Treinamento Físico (n=21, IMC=28±0,5 kg/m2) e Dieta (n=18, IMC=30±0,4 kg/m2). Dez crianças controles magras, da mesma idade, também foram estudadas (IMC=17±0,5 kg/m2). O controle autonômico foi estudado pela variabilidade da freqüência cardíaca. O fluxo sangüíneo do antebraço (FSA) foi mensurado pela técnica de Pletismografia de Oclusão Venosa. A pressão arterial (PA) foi monitorada de forma não-invasiva. O exercício isométrico no \"Handgrip\" foi realizado à 30% da Contração Voluntária Máxima (CVM) por 3 minutos. \"Stroop color word test\" foi realizado durante 4 minutos. Neste estudo, o controle autonômico basal demonstrou atenuado controle parassimpático cardíaco nas crianças com obesidade. A PA basal foi significantemente maior e a Condutância Vascular do Antebraço (CVA) significantemente menor nas crianças obesas. Durante o exercício e o estresse mental, a resposta de PA foi significantemente maior e a CVA significantemente menor nas crianças obesas. Dieta isolada e dieta associada ao treinamento físico reduziram o peso corporal total e o percentual de gordura. Ambos os grupos diminuíram significantemente o nível de PA durante o exercício e o estresse mental. O grupo dieta associada ao treinamento físico, em contraste ao grupo dieta, melhoraram o controle autonômico, em repouso, com aumento da atividade parassimpática cardíaca e diminuição da atividade simpática cardíaca, e significantemente aumento na resposta da CVA durante o exercício (3,7±0,3 vs. 5,6±0,4 unidades, P=0,01) e estresse mental (3,5±0,5 vs. 4,5±0,4 unidades, P=0,02). Após a intervenção com dieta associada ao treinamento físico, as respostas de PA e CVA durante o exercício e o estresse mental foram similares entre o grupo obeso e o grupo controle magro. Conclusão. A obesidade infantil aumenta a resposta de PA e prejudica a resposta vasodilatadora durante o exercício e o estresse mental, e em crianças obesas o controle autonômico cardíaco está alterado. Dieta associada ao treinamento físico restaura a resposta vasodilatadora e a resposta de pressão arterial, e melhora a função do controle autonômico cardíaco / Background. The effects of diet and diet plus exercise training on muscle vasodilatation and autonomic control of heart rate during physiological maneuvers in obese children are unknown. We tested the hypothesis that: 1) autonomic control would be altered in obese children; 2) blood pressure (BP) and forearm vascular conductance (FVC) responses during handgrip exercise and mental stress would be altered in obese children; 3) diet plus exercise training would improve the autonomic control of heart; and 4) diet plus exercise training would restore BP and FVC responses during exercise and mental stress in obese children. Methods and Results. Thirty nine obese children (10±0.2 years) were randomly divided into two groups: Diet plus exercise training (n=21, BMI=28±0.5 kg/m2) and diet (n=18, BMI=30±0.4 kg/m2). Ten age-matched lean control children (NC, BMI=17±0.5 kg/m2) were also studied. Autonomic control was studied by Heart Hate Variability. Forearm blood flow was measured by venous occlusion pletysmography. BP was noninvasively monitored. Handgrip exercise was performed at 30% Maximal Voluntary Contraction (MVC) for 3 minutes. Stroop color word test was performed for 4 minutes. On this study, baseline autonomic control shown decrease impaired heart parasympathetic control in obese children. Baseline BP was significantly higher and FVC significantly lower in obese children. During exercise and mental stress, BP responses were significantly higher and FVC responses significantly lower in obese children. Diet and diet plus exercise training significantly reduced body weight. Diet and diet plus exercise training significantly decreased BP levels during exercise and mental stress. Diet plus exercise training, in contrast to diet, improve the autonomic control with increases parasympathetic activity and decreases sympathetic activity in the obese children heart at rest, and significantly increased FVC responses during exercise (3.7±0.3 vs. 5.6±0.4 units, P=0.01) and mental stress (3.5±0.5 vs. 4.5±0.4 units, P=0.02). After diet plus exercise training, BP and FVC responses during exercise and mental stress were similar between obese children and NC. Conclusions. Obesity exacerbates BP responses and impairs FVC responses during exercise and mental stress in children, and altered autonomic control. Diet plus exercise training restore BP and FVC responses in obese children, and improve autonomic nervous system controls heart function

Introdução: A doença cardiovascular é a principal causa de morbidade e mortalidade em pacientes com síndrome metabólica ou diabetes mellitus tipo 2. Como a disfunção endotelial precede o desenvolvimento da doença cardiovascular, seria desejável identificar e tratar a disfunção endotelial antes que a aterosclerose se desenvolva. Hoje, existe evidência clara para sustentar o efeito protetor do exercício físico regular em pacientes com síndrome metabólica ou diabetes mellitus. O que está menos claro é a relação da intensidade de treinamento e melhora na função endotelial. Objetivo: Avaliar o efeito de um programa de exercício físico, de alta e baixa intensidade, na função endotelial de pacientes com Síndrome Metabólica ou Diabetes Mellitus Tipo 2. Métodos: Foram estudados 31 pacientes com diabetes melittus tipo 2 ou síndrome metabólica, de idade média (±DP) de 58±6 anos, randomizados para treinamento aeróbio de alta intensidade (AI: 75 a 85% freqüência cardíaca máxima, n = 10), treinamento aeróbio de baixa intensidade (BI: 50 a 60% freqüência cardíaca máxima, n = 10) e controle (n = 11). O treinamento foi realizado por 50 minutos, 4 vezes por semana. Antes e após 6 semanas de treinamento, os sujeitos realizaram teste de esforço e estudo da função endotelial, por ultra-som de alta resolução da artéria braquial, avaliados após hiperemia reativa (dependente do endotélio) e após administração de nitrato (independente do endotélio). Resultados: O programa de treinamento aeróbio de alta intensidade resultou em um maior aumento da capacidade funcional, avaliado pelo tempo máximo tolerado no teste de esforço (AI antes 9,39±1,22 minutos e depois 12,12±1,24 minutos; BI antes 8,84s±1,82 minutos e depois 10,41±1,99 minutos; Controle antes 9,36±.1,21minutos e depois 8,96±.1,35minutos; p < 0,05). A diferença no diâmetro do vaso após hiperemia foi significativamente maior para o grupo de alta intensidade (AI antes 4,28±.0,73mm e depois 5,62±.0,95mm; BI antes 4,24±.0,49mm e depois 5,01±.0,56mm; Controle antes 4,31±.0,37mm e depois 4,23±.0,23mm; p < 0,05). Após nitrato, não houve diferença significativa para nenhum dos grupos (AI antes 5,13±.1,17mm e depois 5,20±.1,10mm; BI antes 4,93±.0,88mm e depois 5,07±.0,70mm; Controle antes 4,96±.0,36mm e depois 4,62±.0,36mm; p = 0,565). Conclusões: Quando comparado ao treinamento aeróbio de baixa intensidade e controle, o treinamento aeróbio de alta intensidade melhorou a capacidade funcional e resposta vasodilatadora dependente do endotélio, em pacientes com síndrome metabólica ou diabetes mellitus tipo 2. Estes achados sugerem que o treinamento físico de alta intensidade possa ser considerado como alternativa preventiva nestes pacientes. / Introduction: Cardiovascular disease is the major cause of morbidity and mortality in patients with the metabolic syndrome or diabetes mellitus type 2. As the endothelial dysfunction precedes the development of cardiovascular disease, it would be desirable to identify and treat the endothelial dysfunction before the development of atherosclerosis. There is currently clear evidence to support the protective effect of regular physical exercise on patients with metabolic syndrome or diabetes mellitus. What is less clear is the relationship between training intensity and improvement in endothelial function. Objective: Evaluate effect of a physical exercise program, of high and low intensity, on endothelial function of patients with Metabolic Syndrome or Diabetes Mellitus Type 2. Methods: Thirty one patients with Diabetes Mellitus type 2 or metabolic syndrome were studied, with mean age (±SD) of 58±6 years, randomized for high intensity aerobic training (AI: 75-85% of maximum heart rate, n = 10), low intensity aerobic training (BI: 50-60% maximum heart rate, n = 10) and control (n = 11). The training was performed for 50 minutes, four times a week. Before and after 6 weeks of training, subjects performed the exercise testing and had been studied for endothelial function, by high resolution ultrasound of the brachial artery, assessed after reactive hyperemia (endothelium dependent) and after nitrate administration (endothelium independent). Results: The high intensity aerobic training resulted in a higher increase of the functional capacity, assessed by maximum tolerated time on the exercise testing (AI before 9.39±1.22 minutes and after 12.12±1.24 minutes; BI before 8.84s±1.82 minutes and after 10.41±1.99 minutes; Controls before 9.36±.1.21minutes and after 8.96±.1.35minutes; p < 0.05). The diameter difference of the vessel after hyperemia was significantly higher for the high intensity group (AI before 4.28±0.73mm and after 5.62±0.95mm; BI before 4.24±0.49mm and after 5.01±0.56mm; Controls before 4.31±0.37mm and after 4.23±.0.23mm; p < 0.05). After nitrate, there was no significant difference for none of the groups (AI before 5.13±.1.17mm and after 5.20±.1.10mm; BI before 4.93±.0.88mm and after 5.07±.0.70mm; Controls before 4.96±.0.36mm and after 4.62±.0.36mm; p = 0.565). Conclusions: When compared to the low intensity aerobic training and controls, the high intensity aerobic training improved the functional capacity and vasodilator response endothelium-dependent in patients with metabolic syndrome and diabetes mellitus type 2. These findings suggest that physical training of high intensity might be considered as a preventive alternative in those patients.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-06-22T18:06:10Z No. of bitstreams: 1 alansantospimentel.pdf: 908522 bytes, checksum: 481a497653c77923c89d08522bba1820 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-08-07T19:24:28Z (GMT) No. of bitstreams: 1 alansantospimentel.pdf: 908522 bytes, checksum: 481a497653c77923c89d08522bba1820 (MD5) / Made available in DSpace on 2017-08-07T19:24:28Z (GMT). No. of bitstreams: 1 alansantospimentel.pdf: 908522 bytes, checksum: 481a497653c77923c89d08522bba1820 (MD5) Previous issue date: 2014-03-07 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico / FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais / Objetivo: avaliar o efeito do bloqueio central do receptor AT2 para angiotensina II nas respostas termorregulatórias em ratos durante o exercício físico. Material e métodos: foram utilizados ratos Wistar, não treinados, pesando entre 240-350 g. Os animais portavam cânula no ventrículo cerebral lateral direito para administração de 2 μL de PD (10 μg, n = 7) ou de 0,15 M NaCl (SAL, n = 7). A temperatura corporal interna (Tc), determinada por telemetria através de sensor de temperatura implantado na cavidade intraperitoneal do rato, e a temperatura da cauda (Tcauda) foram medidas durante o repouso e enquanto os animais realizavam exercício submáximo a uma velocidade de 18 m/min, 5 % de inclinação, até a fadiga. A partir dos dados obtidos foram determinados: a taxa de aquecimento corporal (BHR), a taxa de calor acumulado (HSR), o limiar térmico de vasodilatação da cauda (TTcV), o tempo total de exercício (TTE) e o trabalho (W). Resultados: Durante o repouso, a Tc dos animais de ambos os grupos permaneceu estável e diferenças não foram encontradas entre os tratamentos. Observou-se que a administração icv de PD promoveu aumento de 17 % no TTE (18 ± 1,8 min, PD vs. 15 ± 2,1 min, SAL, p < 0,01) e de 20 % no W quando comparado com os controles (4,62 ± 0,34 kgm, PD vs. 3,74 ± 0,4 kgm, SAL, p < 0,01). Apesar dos ratos injetados com PD apresentarem aumento semelhante da Tc durante o exercício físico, no ponto de fadiga verificou-se maior variação da Tc (2,37 ± 0,24 °C, PD; 1,73 ± 0,21 °C, SAL, p< 0,05). Entretanto, durante o exercício físico, diferenças não foram encontradas entre a BHR (0,14 ± 0,01 °C.min-1, PD vs. 0,13 ± 0,02 °C.min-1, SAL), a HSR (33,75 ± 1,37 cal. min-1, PD vs. 30,9 ± 2,82 cal. min-1, SAL) e o TTcV (37,75 ± 0,12 °C, PD vs. 37,61 ± 0,15 °C, SAL) entre os grupos. Adicionalmente, a partir do 13° minuto até a fadiga, a variação da Tcauda foi maior nos animais PD (4,87± 0,44 °C, PD; 3,10 ± 0,57 °C, SAL, p<0,05), que se mostrou intimamente relacionado com o TTE aumentado (r= 0,871, p <0,01). Conclusões: Os dados mostram que o bloqueio do receptor AT2 melhora o balanço térmico durante o exercício físico devido a maior habilidade de dissipar calor, consequentemente contribuindo para aprimoramento do desempenho físico. / Aim: The aim of the study was to verify the effect of central angiotensin ll AT2 receptor blockade in thermoregulatory responses during exercise in rats. Material and methods: Wistar rats weighing between 250 and 350g. Were implanted with a guide cannula in the right lateral cerebral ventricle for administration of 2µL PD (10 μg, n = 7) or 0,15 M NaCl (SAL, n = 7). The internal body temperature (Tb) was determined by telemetry via a temperature sensor implanted in the animal's intraperitoneal cavity. The tail temperature (Ttail) was measured using a temperature sensor attached to the animal's tail. Both temperatures were measured continuously, during resting and while the animals performed submaximal exercise at a speed of 18m/min and 5% inclination, until failure. From the data obtained, body heating rate (BHR), heat storage rate (HSR), body temperature threshold for tail vasodilation (TTbV), time to fatigue (TTF) and workload (W) were determined. Results: Tb remained stable in both group, and no difference was seen between treatments during a resting period. It was observed that icv administration of PD promoted an increase of 17% in the TTF (18 ± 1,8 min, PD vs. 15 ± 2,1 min, SAL, p < 0,01), and of 20% in the W, when compared with controls (4,62 ± 0,34 kgm, PD vs. 3,74 ± 0,4 kgm, SAL, p < 0,01). Despite that the rats injected with PD exhibited similar increase in Tb during exercise, at fatigue point it was found greater variation of Tb (2,37 ± 0,24 °C, PD; 1,73 ± 0,21 °C, SAL, p< 0,05). However, no difference was seen between BHR (0,14 ± 0,01 °C.min-1, PD vs. 0,13 ± 0,02 °C.min-1, SAL), HSR (33,75 ± 1,37 cal. min-1, PD vs. 30,9 ± 2,82 cal. min-1, SAL) and TTbV (37,75 ± 0,12 °C, PD vs. 37,61 ± 0,15 °C, SAL) in both group. Additionally, from the 13° minute of exercise until fatigue, Ttail variation was higher in PD animals (4,87 ± 0,44 °C, PD; 3,10 ± 0,57 °C, SAL, p<0,05), and closely related with the increased TTF (r= 0,871, p <0,01). Conclusion: The data shows that AT2 receptor blockade improves heat balance during exercise due to better ability to dissipate heat, which contributed to superior exercise performance.

L'obésité et le diabète sont associés à des complications cutanées, en particulier des fonctions dermiques impliquées dans le maintien de la résistance mécanique de la peau. Cependant, les mécanismes par lesquels l'obésité provoque la fragilité du tissu cutané sont peu étudiés. Notre travail consistait à évaluer les effets d'un régime hypercalorique sur la microcirculation cutanée et les conséquences sur le développement de lésions cutanées. Les études ont été réalisées chez des souris C57Bl6/J développant une obésité induite par une alimentation enrichie en graisse et en sucre pendant 2, 4, 12 et 20 semaines. Les propriétés de la microcirculation cutanée sont évaluées par les variations du flux sanguin en réponse : 1) à l'acétylcholine afin de déterminer la vasodilatation endothélium-dépendante, 2) au nitroprussiate de sodium afin de déterminer la vasodilatation endothélium-indépendante, 3) à l'application de la pression locale afin de déterminer la vasodilatation induite par la pression (PIV). Ces études sont complétées par des explorations métaboliques (IPGTT, IPITT), morphologiques, immuno-histologiques et biochimiques pour caractériser les quatre modèles. Enfin, chaque modèle a été testé pour l'incidence d'ulcère de pression par l'application d'une pression unique de 85 mmHg. Dans ce travail de thèse, nous avons mis en évidence de nombreux mécanismes de compensation accompagnant l'évolution de l'obésité et qui permettent de maintenir les fonctions vasculaires intactes et permettent de s'adapter à l'environnement inflammatoire induit par l'alimentation hypercalorique. La PIV est un outil de diagnostic nous permettant d'évaluer l'intégrité de la fonction neurovasculaire et prédire l'incidence de lésions cutanées / Obesity and diabetes are associated to skin pathophysiology, particularly the dermal functions involved in maintaining the skin’s mechanical strength. The underlying mechanisms in pressure ulcer during obesity remain unclear. In this study we evaluated the effects of a hypercaloric diet on the cutaneous microcirculation and its consequences on pressure sores. C59Bl6/J mice were fed a high fat and high sugar diet during 2, 4, 12 and 20 weeks. Microvascular properties were assessed by measuring the skin blood flow variations in response to 1) acetylcholine in order to determine the endothelium-dependent vasodilation, 2) sodium nitroprusside in order to determine the endothelium-independent vasodilation, 3) local pressure application in order to determine the pressure-induced vasodilation (PIV). Each model was characterized for metabolic assessment (IPGTT, IPITT), hisological, immune-histological and biochemical measurements. Finally, each model was tested for pressure ulcer incidence with a 85 mmHg pressure application on skin layers. In this study, we found that obesity is a pathology in constant evolution that is associated with many compensatory mechanisms for maintaining vascular functions and for the adaptation of the skin tissue to an inflammatory environment induced by a hypercaloric diet. PIV has become a useful tool for pressure ulcer prediction

Le vieillissement diminue les propriétés mécaniques protectrices de la peau qui prédispose le sujet âgé aux ulcères de pression, les escarres. Ce travail a pour objectif de (1) tester les capacités de défense de la peau face aux contraintes mécaniques au cours du vieillissement, (2) identifier les facteurs responsables de la dégénérescence des capacités de protection de la peau avec l'âge et (3) évaluer les effets d'un traitement chronique anti-oxydant. Les capacités de résistance de la peau aux pressions ainsi que l'incidence d'escarres suite à une ischémie prolongée ont été étudiées chez des rats jeunes (6 mois), matures (12 mois) et âgés (24 mois) de deux souches : Brown Norway (longévité accrue), et Wistar. Des études complémentaires ont permis d'identifier les facteurs responsables de cette dégénérescence, en particulier le versant vasculaire, l'atteinte nerveuse sensorielle et les modifications de la structure et des propriétés visco-élastiques de la peau. L'efficacité du traitement anti-oxydant sur les capacités mécaniques protectrices de la peau a été estimée. Les résultats montrent une altération des propriétés mécaniques protectrices de la peau avec l'âge, plus ou moins précoce selon la souche de rats, associée à une atteinte fonctionnelle vasculaire (chez les rats Wistar), l'installation progressive d'une neuropathie périphérique sensorielle et d'un défaut visco-élastique cutané dans les deux souches de rats. Ces atteintes ne reflètent pas systématiquement la fragilité de la peau âgée face aux escarres, modulée par l'état du tissu adipeux. Le traitement antioxydant permet de réduire plusieurs atteintes mais a induit des effets contradictoires entre les deux souches de rats étudiées vis-à-vis de l'incidence d'escarres / The aging decreases the protective properties of the skin, which predisposes the aging subject to pressure ulcers. This thesis had for objective (1) to test the defence capacities of the skin to resist mechanical stress during aging, (2) identify the factors responsible for the degeneration of the protection capacity of the aging skin and (3) evaluate the effects of a chronic antioxidant treatment. To meet this three objectives, the cutaneous responses to pressures of different intensities together with the pressure ulcer incidence following a prolonged ischemia were studied on 3 different ages of rats: young (6 months), mature (12 months) and aged (24 months). Those 3 stages of aging were studied on 2 different rat strains: “Brown Normay”, healthy aging model with an accrued longevity and “Wistar”, control rats. Complementary studies allowed identifying the mechanism who leads to a diminution of the protective capacities of the skin. In particular, the vascular dysfunctions (endothelial and smooth muscular cells), the sensory nervous dysfunctions, the modifications of the skin structure and the viscoelastic properties were evaluated. The efficiency of the anti-oxidant treatment was estimated focusing principally on the effects on the nervous and vascular capacities, the structure of the skin and the impact of the pressure ulcer. The results show that the aging induces a more or less early alteration of the protective properties of the skin in response to pressures, more or less precocious depending on the strain of the rat. The decrease of the natural defences is associated to a vascular dysfunction (endothelium with the Wistar rats), the progressive installation of a sensory peripheral neuropathy and a deterioration of cutaneous viscoelastic properties with the two strains of rats. These deteriorations do not reflect systematically the fragility of the aged skin towards pressure ulcers, modulated by the state of the subcutaneous adipose tissue. The chronic anti-oxidant treatment allows to reduce several dysfunctions but has induced contradictory effects between the two studied strains of rats towards the incidence of pressure ulcers

O BPP-10c é um decapeptídeo bioativo, rico em resíduos de prolina e é expresso em uma proteína precursora no cérebro e na glândula de veneno da Bothrops jararaca. Recentemente demonstramos que o BPP-10c tem um potente e sustentado efeito anti-hipertensivo em ratos espontaneamente hipertensos (SHR), sem, no entanto, causar qualquer efeito em ratos normotensos, por um mecanismo farmacológico independente da inibição da enzima conversora de angiotensina (ECA), levando à hipótese de que outro mecanismo poderia estar envolvido na atividade do peptídeo. Neste trabalho, usamos cromatografia de afinidade para isolar e identificar as proteínas renais com afinidade pelo BPP-10c e demonstramos que a argininosuccinato sintase (AsS) é a principal proteína a se ligar ao peptídeo. Além disso, mostramos que essa interação promove um aumento na atividade catalítica da enzima, de forma dose-dependente. A AsS é reconhecida como uma peça chave na regulação do ciclo da citrulina-óxido nítrico (NO), e sua ação é passo limitante na síntese de NO. A interação funcional do BPP-10c com a AsS foi evidenciada pelos seguintes efeitos promovidos pelo peptídeo: i) estimulação da produção de NO por células HUVEC e da produção de arginina por células HEK 293, ii) aumento da concentração plasmática de arginina em SHR. Corroborando esses achados, mostramos a reversão dos efeitos do peptídeo, inclusive sobre a pressão arterial em SHR, quando o MDLA, um inibidor específico da AsS, foi co-administrado. Em conjunto, os resultados apresentados neste trabalho sugerem que a AsS é fundamental para o efeito anti-hipertensivo do BPP-10c. Tais resultados nos levaram a propor a AsS como um novo alvo terapêutico, e o BPP-10c como molécula-líder para a geração de medicamentos para tratamento de doenças relacionadas à hipertensão arterial / BPP-10c is a bioactive proline-rich decapeptide, part of the C-type natriuretic peptide precursor, expressed in the brain and in the venom gland of Bothrops jararaca. We recently showed that BPP-10c displays a strong, sustained anti-hypertensive effect in spontaneous hypertensive rats (SHR), without causing any effect in normotensive rats, by a pharmacological mechanism independent of angiotensin converting enzyme inhibition; therefore, we hypothesized that another mechanism should be involved in the peptide activity. Here we used affinity chromatography to search for kidney cytosolic proteins with affinity for BPP-10c and demonstrate that argininosuccinate synthetase (AsS) is the major protein binding to the peptide. More importantly, this interaction activates the catalytic activity of AsS in a dose-dependent manner. AsS is recognized as an important player of the citrulline-nitric oxide (NO) cycle that represents a potential limiting step in NO synthesis. Accordingly, the functional interaction of BPP-10c and AsS was evidenced by the following effects promoted by the peptide: i) increase of NO production in human umbilical vein endothelial cell culture, and of arginine in human embryonic kidney cells; ii) increase of arginine plasma concentration in SHR. Moreover, MDLA, a specific AsS inhibitor, significantly reduced the anti-hypertensive activity of BPP-10c in SHR. These results led us to suggest AsS as a new therapeutically useful target for the development of activators, such as BPP- 10c, useful to treat hypertension related diseases

Ce projet illustre cinq études, mettant l'emphase sur le développement d'une nouvelle approche diagnostique cardiovasculaire afin d'évaluer le niveau d’oxygène contenu dans le myocarde ainsi que sa fonction microvasculaire. En combinant une séquence de résonance magnétique cardiovasculaire (RMC) pouvant détecter le niveau d’oxygène (OS), des manœuvres respiratoires ainsi que des analyses de gaz artériels peuvent être utilisés comme procédure non invasive destinée à induire une réponse vasoactive afin d’évaluer la réserve d'oxygénation, une mesure clé de la fonction vasculaire. Le nombre de tests diagnostiques cardiaques prescrits ainsi que les interventions, sont en pleine expansion. L'imagerie et tests non invasifs sont souvent effectués avant l’utilisation de procédures invasives. L'imagerie cardiaque permet d’évaluer la présence ou absence de sténoses coronaires, un important facteur économique dans notre système de soins de santé. Les techniques d'imagerie non invasives fournissent de l’information précise afin d’identifier la présence et l’emplacement du déficit de perfusion chez les patients présentant des symptômes d'ischémie myocardique. Néanmoins, plusieurs techniques actuelles requièrent la nécessité de radiation, d’agents de contraste ou traceurs, sans oublier des protocoles de stress pharmacologiques ou physiques. L’imagerie RMC peut identifier une sténose coronaire significative sans radiation. De nouvelles tendances d’utilisation de RMC visent à développer des techniques diagnostiques qui ne requièrent aucun facteur de stress pharmacologiques ou d’agents de contraste. L'objectif principal de ce projet était de développer et tester une nouvelle technique diagnostique afin d’évaluer la fonction vasculaire coronarienne en utilisant l' OS-RMC, en combinaison avec des manœuvres respiratoires comme stimulus vasoactif. Ensuite, les objectifs, secondaires étaient d’utilisés l’OS-RMC pour évaluer l'oxygénation du myocarde et la réponse coronaire en présence de gaz artériels altérés. Suite aux manœuvres respiratoires la réponse vasculaire a été validée chez un modèle animal pour ensuite être utilisé chez deux volontaires sains et finalement dans une population de patients atteints de maladies cardiovasculaires. Chez le modèle animal, les manœuvres respiratoires ont pu induire un changement significatif, mesuré intrusivement par débit sanguin coronaire. Il a été démontré qu’en présence d'une sténose coronarienne hémodynamiquement significative, l’OS-RMC pouvait détecter un déficit en oxygène du myocarde. Chez l’homme sain, l'application de cette technique en comparaison avec l'adénosine (l’agent standard) pour induire une vasodilatation coronarienne et les manœuvres respiratoires ont pu induire une réponse plus significative en oxygénation dans un myocarde sain. Finalement, nous avons utilisé les manœuvres respiratoires parmi un groupe de patients atteint de maladies coronariennes. Leurs myocardes étant altérées par une sténose coronaire, en conséquence modifiant ainsi leur réponse en oxygénation. Par la suite nous avons évalué les effets des gaz artériels sanguins sur l'oxygénation du myocarde. Ils démontrent que la réponse coronarienne est atténuée au cours de l’hyperoxie, suite à un stimuli d’apnée. Ce phénomène provoque une réduction globale du débit sanguin coronaire et un déficit d'oxygénation dans le modèle animal ayant une sténose lorsqu’un supplément en oxygène est donné. En conclusion, ce travail a permis d'améliorer notre compréhension des nouvelles techniques diagnostiques en imagerie cardiovasculaire. Par ailleurs, nous avons démontré que la combinaison de manœuvres respiratoires et l’imagerie OS-RMC peut fournir une méthode non-invasive et rentable pour évaluer la fonction vasculaire coronarienne régionale et globale. / This project encompasses five studies, which focus on developing a new cardiovascular diagnostic approach for assessing myocardial oxygenation and microvascular function. In combination with oxygenation-sensitive cardiovascular magnetic resonance (OS-CMR) imaging, breathing maneuvers and altered arterial blood gases can be used as a non-invasive method for inducing a vasoactive response to test the oxygenation reserve, a key measurement in vascular function. The number of prescribed cardiac diagnostic tests and interventions is rapidly growing. In particular, imaging and other non-invasive tests are frequently performed prior to invasive procedures. One of the most common uses of cardiac imaging is for the diagnosis of significant coronary artery stenosis, a critical cost factor in today’s health care system. Non-invasive imaging techniques provide the most reliable information for the presence and location of perfusion or oxygenation deficits in patients with symptoms suggestive of myocardial ischemia, yet many current techniques suffer from the need for radiation, contrast agents or tracers, and pharmacological or physical stress protocols. CMR imaging can identify significant coronary artery stenosis without radiation and new trends in CMR research aim to develop diagnostic techniques that do not require any pharmacological stressors or contrast agents. For this project, the primary aim was to develop and test a new diagnostic technique to assess coronary vascular function using OS-CMR in combination with breathing maneuvers as the vasoactive stimulus. Secondary aims then used OS-CMR to assess myocardial oxygenation and the coronary response in the presence of altered arterial blood gases. An animal model was used to validate the vascular response to breathing maneuvers before translating the technique to human subjects into both healthy volunteers, and a patient population with cardiac disease. In the animal models, breathing maneuvers could induce a significant change in invasively measured coronary blood flow and it was demonstrated that in the presence of a haemodynamically significant coronary stenosis, OS-CMR could detect a myocardial oxygen deficit. This technique was then applied in a human model, with healthy participants. In a direct comparison to the infusion of the coronary vasodilator adenosine, which is considered a standard agent for inducing vasodilation in cardiac imaging, breathing maneuvers induced a stronger response in oxygenation of healthy myocardium. The final study then implemented the breathing maneuvers in a patient population with coronary artery disease; in which myocardium compromised by a coronary stenosis had a compromised oxygenation response. Furthermore, the observed effects of arterial blood gases on myocardial oxygenation were assessed. This demonstrated that the coronary response to breath-hold stimuli is attenuated during hyperoxia, and this causes an overall reduction in coronary blood flow, and consequently an oxygenation deficit in a coronary stenosis animal model when supplemental oxygen is provided. In conclusion, this work has improved our understanding of potential new diagnostic techniques for cardiovascular imaging. In particular, it demonstrated that combining breathing maneuvers with oxygenation-sensitive CMR can provide a non-invasive and cost-effective method for assessing global and regional coronary vascular function.

La compression nerveuse chronique (CNC) est un modèle d’étude expérimental définit pour l’examen du syndrome du canal carpien. Notre travail consistait à étudier chez le rat sain, l’effet d’une CNC de courte ou de longue durée sur la microcirculation cutanée, ainsi que la capacité de récupération fonctionnelle du nerf suite à une décompression, et les mécanismes moléculaires impliqués dans la régénération nerveuse. L’originalité de l’équipe de recherche est d’avoir montré un mécanisme physiologique original permettant d’étudier l’interaction neurovasculaire cutanée qui peut être observée sur le nerf. La PIV (Pressure‐Induced Vasodilation) est un outil original de commande de la vasomotricité par les fibres C. Les dysfonctions neurovasculaires cutanées et nerveuses induites par une CNC de courte durée sont associés à l’altération des fibres C et, à des mécanismes angiogéniques et inflammatoires du nerf lésé. Ces atteintes sont réversibles après une décompression nerveuse, malgré une modification de la balance des facteurs angiogéniques, une augmentation de l’expression de facteurs inflammatoires et l’activité de protéines à profil apoptotique. La CNC de longue durée provoque des traumatismes plus importants auxquels s’ajoutent des atteintes vasculaires. Par conséquent la décompression du nerf sciatique n’a pas permis de rétablir les fonctions nerveuses périphériques. La PIV fournit un diagnostic précoce de l’atteinte nerveuse suivant sa réduction, synonyme d’une CNC de courte durée, ou de son abolition, synonyme d’une CNC longue durée. Ces niveaux d’atteintes nerveuses et inflammatoires pourraient être responsables ou non de la récupération fonctionnelle nerveuse / Chronic nerve compression (CNC) is an experimental study model for the examination of the carpal tunnel syndrome. Our work aimed to study the effect of short or long‐term CNC on the cutaneous blood flow, on the nerve ability to recover following to nerve release, and the molecular mechanisms involved in the nervous regeneration. For that purpose, our laboratory established an original physiological mechanism in the study of the relationship between vessel and nerve in the sciatic nerve but also at the periphery, in the cutaneous tissue. Therefore, PIV (Pressure‐Induced Vasodilation) is an original tool of vasomotion linked to C‐fibers. Cutaneous and nervous neurovascular dysfunctions induced by a shortterm CNC were associated to cutaneous C‐fibers impairment and, angiogenic and inflammatory mechanisms of the injured nerve. These achievements are reversible after nerve release, even though the nerve showed a modification of the balance of angiogenic factors, an increase of the expression of inflammatory factors and the activity of proteins with apoptotic type. The long‐term CNC induced more important trauma that further affected the vascular function. Consequently the decompression of the sciatic nerve did not allow restoring the peripheral nervous function. PIV allows to early diagnosing nerve damage with a reduction referring to a short‐term CNC or an abolition referring to a long‐term CNC. Activation of the inflammatory pathway during CNC could compromise nerve recovery following nerve decompression

No description available.

L’obésité et le diabète sont associés à des complications, notamment une fragilité cutanée. Celle-ci pourrait être associée à une altération du métabolisme du glucose et à une augmentation du tissu adipeux sous-cutané. Il a été montré que l’hypoderme pourrait avoir une fonction spécifique pour la peau. Notre travail a consisté d’une part à caractériser l’adiposité hypodermique et à étudier son influence dans la réactivité du tissu cutané en réponse à des pressions faibles ou fortes chez des souris obèses et d’autre part à étudier le processus de cicatrisation. Les fortes pressions augmentent la fragilité cutanée ce qui peut aboutir à des lésions, notamment des ulcères de pression. Les études ont été réalisées chez des souris C57BL/6J développant une obésité induite par une alimentation riche en lipides et en sucres pendant 4 et 12 semaines. La taille des adipocytes de l’hypoderme a été mesurée ainsi que leur réponse lipolytique en présence ou non d’insuline. La réactivité tissulaire a été évaluée en mesurant les variations du flux sanguin en réponse : 1) à l’application d’une pression locale faible afin de déterminer la vasodilatation induite par la pression (PIV), 2) par iontophorèse d’acétylcholine ou de nitroprussiate de sodium. Afin d’explorer le processus spécifique d’ulcère de pression chez les souris obèses diabétiques, une compression par cycles d’ischémie-reperfusion a été réalisée. Ces études ont été complétées par des explorations métaboliques, histologiques et biochimiques. Par ailleurs nous avons déterminé l’impact de l’augmentation de l’adiposité sur des fibroblastes dermiques in vitro afin de mieux comprendre le processus de cicatrisation.Dans ce travail de thèse, nous avons mis en évidence une augmentation de l’adiposité hypodermique associée à une insulinorésistance tissulaire et systémique. Nous avons également montré un retard de cicatrisation en fonction de l’évolution de l’obésité et des réponses micro vasculaires diminuées post cicatrisation par rapport à une peau non lésée / Obesity and diabetes led to complications, including skin fragility. Skin fragility could be associated to a glucose metabolism alteration and a subcutaneous adipose tissue increase. It has been shown that hypodermis could have a specific function for the skin. Our work consisted on the one hand in characterizing the dermal adiposity and studying its involvement in the skin tissue reactivity in response to low or high pressures in obese mice and, on the other hand, in studying the healing process. High pressures increase cutaneous fragility which can lead to skin wounds, in particular pressure ulcers. This study was realized using C57BL/6J male mice with a diet-induced obesity. C57BL/6J mice were fed a high fat and high sugar diet during 4 or 12 weeks. Hypodermis adipocytes size was measured as well as their lipolytic response in presence or absence of insulin. The skin tissue reactivity was assessed measuring the skin blood flow variations in response to 1) a local pressure application in order to determine the pressure-induced vasodilation (PIV), 2) an acetylcholine or sodium nitroprusside iontophoresis. To examine the specific mechanism of the pressure ulcer in obese diabetic mice, a compression with ischemia-reperfusion cycles was realized. Metabolic assessment, histological and molecular biological studies were carried out to characterize each stage of healing through obesity. Furthermore, we determined the adiposity increase on dermal fibroblasts in vitro to better understand the healing process. In this thesis work, we have highlighted a hypodermis adiposity linked to a tissue and a systemic insulin resistance. We have also showed a delayed healing depending on the evolution of the obesity. The microvascular responses were decreased post healing compared to a non-wounded skin